johnsanc Posted November 17, 2019 Share Posted November 17, 2019 Apologies if this was asked before - but is there a way to pinpoint exactly what is causing excessive writing to my two 1TB SDDs in my cache pool? I have had these drives less than one year and they are already nearing 500 TBW - which is insane!!! I have a feeling it's a docker that is writing a ton of temp files or something. This is a huge issue as I have burned through the useful life of these drives in less than 1/4th the warranty period. I didn't even notice the wear until I checked the smart reports today. Any help getting to the bottom of this is appreciated, as well as any tips for preventing this excessive usage. (This would be a great thing to include as a test in Fix Common Problems) Quote Link to comment
Squid Posted November 17, 2019 Share Posted November 17, 2019 Netdata / cAdvisor should help pinpoint it. Or via a command prompt, iotop Quote Link to comment
johnsanc Posted November 17, 2019 Author Share Posted November 17, 2019 (edited) I tried using iotop and I noticed similar results as these two threads below Initially I saw a ton of writes coming from shfs (100-200mb/s steady). I disabled my Nextcloud docker and it immediately reduced the disk writes. I turned Nextcloud back on and things seem relatively normal... I see loop2 now has the most writes but its not crazy like before. Its at about 2GB in 15 minutes. Is there a bug with Nextcloud or something? I checked my access logs and no one was logged in and there were no transfers. Here you can see a near constant write of 250mb/s until I restarted Nextcloud just a few moments ago near the end of the timeline. Whatever this issue is it doesn't happen immediately. According to the disk graph it started after about 7 hours of uptime. I guess I'll check on this tomorrow morning to see if the disk usage is excessively high again. Edited November 17, 2019 by johnsanc Quote Link to comment
BRiT Posted November 17, 2019 Share Posted November 17, 2019 Others have identified using BTRFS with Encyption as a common cause of excessive writes. Quote Link to comment
johnsanc Posted November 17, 2019 Author Share Posted November 17, 2019 I use BTRFS on my cache drives, but no encryption. Quote Link to comment
johnsanc Posted November 17, 2019 Author Share Posted November 17, 2019 One thing I noticed is that my docker config is set to /mnt/user/appdata instead of /mnt/cache/appdata Could that be causing an issue?Sent from my iPhone using Tapatalk Quote Link to comment
johnsanc Posted November 17, 2019 Author Share Posted November 17, 2019 (edited) OK - So I woke up this morning and lo and behold it was writing like crazy again. Shut off Nextcloud and it stopped completely. No other changes were made. The mover started at 3:30 AM so I assume that is the first bump of writes, but then it kicks up at about 4:20 AM. Does anyone have any idea what Nextcloud is doing in the background that might be causing this? I assume I cannot be the only person this is happening to. Edit: This appears to be oc_filecache updates... but still not sure why it seems to perpetually update once it starts. Edited November 17, 2019 by johnsanc Quote Link to comment
johnsanc Posted November 18, 2019 Author Share Posted November 18, 2019 I think I figured this out - and its totally user error and not being careful and mounting something as external storage that I shouldn't have. Basically there where two issues: 1) Nextcloud does NOT index symlinks properly. I had literally millions of rows in the oc_filecache that were junk looped paths due to symlinks 2) Something that was mounted was symlinked to system paths where files change basically non-stop, which causes constant modified date updates I ended up having well over 400 million rows. Instead of cleaning it up I just truncated the entire oc_filecache table and starting fresh with correct external storage mounts. At least 1 TB 860 EVO drives are on sale for $105 at Best Buy for black friday... Quote Link to comment
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